Scanning Probe Identifies Asphaltenes

Petroleum crude oil is an incredibly complex mixture, possibly containing more than 100,000 unique chemical compounds. Asphaltenes, a large group of polycyclic aromatic molecules containing alkyl chains, heteroatoms, and metals, are high-molecular-weight petroleum components that thwart oil recovery efforts and foul transport pipelines, refinery equipment, and catalysts. Detailed knowledge of asphaltene structures and other properties could help researchers relieve these problems and find uses for the materials. Yet because of asphaltenes’ complexity, diversity, and tendency to aggregate, researchers have struggled to identify the molecules’ structures. That information may soon be widely available from a method that combines atomic resolution imaging via atomic force microscopy and molecular orbital imaging from scanning tunneling microscopy (J. Am. Chem. Soc. 2015, DOI: 10.1021/jacs.5b04056). Bruno Schuler and Leo Gross of IBM Research in Zurich and colleagues, who developed the method, used it to reveal the structures of more than 100 asphaltene molecules ranging widely in composition, size, and shape.